1. Field of the Invention
The present invention relates generally to lipid membranes.
2. Description of Related Art
Protein pores, such as alpha-Hemolysin, have been shown to act as stochastic sensors for a wide range of target molecules. A protein pore is used to reconstitute a planar phospholipid bilayer membrane. A black lipid membrane (BLM) is formed on a thin Teflon partition with a hole in the middle several tens of microns in diameter. The partition separates identical aqueous media (e.g. 1 M KCl with buffer at neutral pH) in a trough. A voltage is applied so as to drive an ionic current through the open pore. If single stranded DNA is introduced into the cis chamber (the chamber with the negative electrode) current blockades are observed during polyanionic DNA translocation through the protein pore into the opposite trans chamber. (Henrickson et al., “Driven DNA Transport into an Asymmetric Nanometer-Scale Pore,” Phys. Rev. Lett., 85, 3057 (2000). All referenced publications and patent documents are incorporated herein by reference.) The bilayer membrane in these studies is made of non-polymerizable phospholipids. Experiments designed to study protein channels in such lipids typically last only a few hours after which the membrane becomes unstable.
Protein ionic channels in planar lipid bilayer membranes permit the study of ion and macromolecular transport through single or multiple nanometer-scale pores. Nearly four decades since this in vitro system was developed liquid-crystalline membranes limit the use of protein nanopores for real-world applications because of the weak intermolecular interactions that stabilize phospholipid membranes.
Ion channels provide the molecular basis for nerve activity and mediate the selective transport of ions and macromolecules. In addition, some ion channels connect cells together to form large-scale functioning tissue whereas others act as lethal toxins. It has been shown that channels could act as components of sensors to detect a variety of analytes including ions and small molecules polynucleotides, and proteins. Black lipid membranes (BLMs), phospholipid bilayers that span small apertures, have provided a convenient platform for most of these studies. However, conventional planar lipid bilayer membranes are too fragile to be used in analytical applications and for long-term studies of ion channels.